Case IH 422 – Engine Controller (ENG / ECM): Engine Coolant Level Sensor (optional) has failed or the jumper plug is missing

The system detects an erratic, intermittent, or incorrect data signal. Specifically, voltage is detected simultaneously on both the coolant level high and low signal pins (pins 24 and 22 of the sensor harness connector), or no voltage is detected on both pins. Because of this fault, the machine will have no engine protection for low coolant levels.

• MX Magnum
• STX Steiger
• MX series
• TG series
• CX series
• Steiger tractors
• Magnum series
• Axial-Flow combines (1640 through 2588 series)
• CPX cotton pickers
• Terragator models

1. 1

   Check the coolant level in the reservoir and top up as required. Inspect the radiator core for debris and clear any blocked airflow.

2. 2

   Verify if your machine is equipped with the optional coolant level sensor. If it is not, check the harness to ensure the factory jumper plug is installed and secure.

3. 3

   Disconnect the sensor harness connector (P183). Switch the key ON (engine not running) and use a voltmeter to check for 5V at pin 7 on the harness coming from the engine.

4. 4

   Check the wiring harness for damage, bent, loose, or corroded pins, and loose connectors.

5. 5

   With the key switched off, unplug the connector (P30) at the coolant level sensor. Install a jumper wire from pin A to pin C and from pin B to pin C to see if the code clears (Bypass Test).

1. 1

   Top off fluids

   Ensure the coolant reservoir is filled to the correct specification.

2. 2

   Address the Jumper Plug

   If the machine does not use a coolant level sensor and the bypass jumper plug is missing or damaged, install a new jumper plug to close the circuit.

3. 3

   Repair Wiring

   If the voltage test yielded less than 5V or physical damage was found, repair the faulty wire or replace the damaged section of the engine harness.

4. 4

   Replace the Sensor

   If the harness provides the correct 5V reference but the sensor fails the bypass test (or is physically leaking/damaged), remove the old sensor from the reservoir/radiator and install a replacement coolant level sensor.

5. 5

   Clear Codes

   Cycle the key and use a diagnostic tool to clear the inactive fault code 422.